Two things:
1. there are some huge glaring things I (and others) don't like about Johnson. Whether you or others like it or not, it's a glaring concern for some. And they are not trivial and to be glossed over. Austin Peterson was a much better 3rd party option to me.
2. Wanting him to be viable. And thinking he should be. Are both much different than him ever being viable. I would love a 3rd party to be viable. But it just isn't so right now. There is a hope and a reality. And they are far apart at the moment.
Unlike Peterson, Johnson AND HIS RUNNING MATE William Weld were both extremely successful two-term REPUBLICAN governors in VERY BLUE states.
That speaks to both of your points 1 & 2.
1. They are more Republican than Trump is. They have the credentials, the voting history, and frankly the stated policy positions to prove it.
2. They were hugely successful Republicans in Blue states, but can't be successful in a general? But Trump with his daily idiotic statements like the one we are discussing today, flip-flopping, and flat out left-authoritarian policies is somehow more viable? The Celebrity Apprentice guy?